A Framework for the Comparative Assessment of Neuronal Spike Sorting Algorithms towards More Accurate Off-Line and On-Line Microelectrode Arrays Data Analysis

Figure 6

Comparison of the separability of simulated spikes in the feature space. (a) Example of projections of the spikes extracted from a simulated signal (i.e., signal #10 of Figure 2) in each feature space (PCA: Principal Components Analysis, DWT: Discrete Wavelet Transform, GEO: geometric features, and FSDE: First and Second Derivative Extrema), colored according to the real labels. (b) Cluster validity (CV) values obtained after the application of the 4 feature extraction methods to the 36 simulated extracellular signals. (c) Cluster validity dependence on different noise levels (median of CV values for each SNR group). (d) Box-plots (median and IQR with whiskers delimited by the maximum and minimum nonoutliers values) of CV values on all the simulated signals (). The asterisks above each method indicate statistically highest CV values of the current method compared to the method(s) coded by the asterisks’ color (Wilcoxon’s matched pair test with ).

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